Bakteeriseinissä

Bakteeriseinissä, or bacterial cell walls, are crucial structures that surround the plasma membrane of bacterial cells. They provide mechanical support, maintain cell shape, and protect the bacterium from osmotic lysis, a process where water rushes into the cell causing it to burst. The composition of bacterial cell walls varies significantly between different types of bacteria, forming the basis for Gram staining, a fundamental diagnostic technique in microbiology.

Gram-positive bacteria have a thick layer of peptidoglycan, a polymer unique to bacteria, located outside the plasma membrane. This peptidoglycan layer is responsible for retaining the crystal violet stain used in Gram staining, making these bacteria appear purple under a microscope. In contrast, Gram-negative bacteria possess a much thinner peptidoglycan layer situated between the plasma membrane and an outer membrane. This outer membrane contains lipopolysaccharides, which can act as endotoxins. Due to their thinner peptidoglycan layer and the presence of the outer membrane, Gram-negative bacteria do not retain the crystal violet stain and instead take up the counterstain, appearing pink or red.

The synthesis and maintenance of the bacterial cell wall are essential for bacterial survival and are targeted by many antibiotics, such as penicillin, which inhibit peptidoglycan synthesis. This makes the bacterial cell wall a critical target for antimicrobial therapies. The diversity in cell wall structures reflects the wide range of environments bacteria inhabit and their evolutionary adaptations.